射频电路设计与应用07(英文).pdf

《射频电路设计与应用07(英文).pdf》由会员上传分享，免费在线阅读，更多相关内容在教育资源-天天文库。

1、CityUniversityofHongKongEE6601TopicsinRadioFrequencyCircuitDesignandApplicationsLecture7FoundationsofRFIDProfessorQuanXUEEmail:eeqxue@cityu.edu.hkContactNumber:344246801WhatisRFID1.WhatisRFID2.PassiveRFID3.ActiveRFID2FromBarCodetoRFID(RadioFrequencyIdentification)1234567890128>Re

2、ader,BarcodeQRcode•BarcodeorQRcodereadersnormallyrequirealine-of-sighttransmission.Theymustbeviewableonthesurfaceofanobject.•Bar/QRcodescontainlimitedinformation.•Informationcontainedinbar/QRcodescannotbechanged.3Whatdoesthebarcodetellyou?EAN-1301234567890128CompanyPrefixItemRefe

3、renceCheckDigit1234567890128>WhatdoestheEPC(ElectronicProductCode)tellyou?Header-----------------------Identifiesthelength,type,structure,version,andgenerationoftheEPCEPCManagerNumber-----CompanyresponsibleformaintainingthesubsequentpartitionsObjectClass-----------------Itemclass

4、identificationSerialNumber--------------IdentifiestheinstanceEPC96bitsstructureHeaderEPCManagerObjectSerialNumberBits8342034Values0-2560-17,179,869,1830-1,1048,5750-17,179,869,1834FromBarCodetoRFID(RadioFrequencyIdentification)RFIDCardReaderRFIDTag•RFIDdonotrequirealine-of-sightt

5、ransmission.•RFIDprovideshighreadrate.•RFIDcancontainmuchmoreinformation•RFIDcanbenotonlyread,butalsowritten.5TypesofTagsPassivePassiveRFIDreliesonRFenergytransferredfromthereadertothetagtopowerupthetag.PassiveRFIDrequiresstrongRFsignalsfromthereader,andtheRFsignalstrengthretur

6、nedfromthetagisconstrainedtoverylowlevelsbythelimitedenergy.ActiveActiveRFIDusesaninternalpowersource(abattery)withinthetagtocontinuouslypowerthetaganditsRFcommunicationcircuitry.6ComparisonBetweentheActiveandPassiveTagsActiveRFIDPassiveRFIDTagPowerSourceInternaltotagEnergytran

7、sferredusingRFfromreaderTagBatteryYesNoAvailabilityofContinuousOnlyinfieldofreaderpowerRequiredsignalVeryLowVeryHighstrengthtoTagRangeUpto100mUpto2-7m,usuallylessDataStorageLargerSmaller7ClassesofTagsClass5Class4capabilitiesplustheabilitytocommunicatewithpassivetagsClass4Class3ca

8、pabilitiesplusactivecommunicationClass3C